Nest E & Baxi 228 OpenTherm issue

[astral_image]

Nope, and now that you mention it the problem wasn't there when the boiler and heatlink were on but not yet set up. As soon as I got to the equipment stage of setup and confirmed the settings in my last post, the boiler kicked in to heat DHW.

 

[Deleted member 267285]

I wonder if the issue is with the hot water side? The Nest might not be compatible with that side of it? Are you able to setup as heating only?

 

[astral_image]

The DHW settings are fairly limited with the Nest in combi mode. Perhaps I need to have a play around in system boiler mode? I think the settings open up a bit then.

 

[astral_image]

Okay, I had a play around with the settings. Selecting either "other" or "system" boiler, then "not connected" for the hot water seems to solve the problem. The boiler is now in charge of the DHW temperature via the dial on the front, and the boiler hasn't fired up randomly to heat DHW.

Is there any difference between combi, system or other when it comes to the central heating (set to OpenTherm)?

 

[astral_image]

Also, does this wiring look okay? I had to bend the live and neutral wires more than I'd like to get the cable into the clamp (the connector contains the old switch wire).

Many thanks again for all your help!

 

[Notch7]

This is a known issue with Baxi as they've not implemented OpenTherm in the way you might expect. The Nest 3rd Gen works, Nest e doesn't. Honeywell T6R-HW works, the old T6 Lyric single channel (now discontinued) didn't. Their boilers require a certain hot water control ID to be transmitted to the boiler by the thermostat and not all controls do this.

Hi Muggles, apologies for restarting an old thread, but I wondered if Main / Baxi still have this same issue

Also would you know if EPH controls would send hot water control ID to make a Baxi boiler work.

I was thinking of the EPH hot water priority pack

Priority Hot Water Pack - PDHW - EPH Controls

This pack ensures higher efficiency with lower demand on the boiler. Allows flow and return temperatures to be reduced thereby increasing the efficiency of the heating circuitLower flow and return temperatures ensure the boiler operates within its condensing range.Connecting the OFF contact of...

www.ephcontrols.com

 

[muggles]

Not sure to be honest, I don't fit Baxi so not always 100% up to date on their latest software developments

 

[Notch7]

Not sure to be honest, I don't fit Baxi so not always 100% up to date on their latest software developments

Hi Muggles, thank you for the reply anyway

Ive done a fair bit of googling on hot water priority and optimising system design to help boilers condense and thus work at high efficiency ratings and its surprising how little information there is out there especially given latest building regs.


Intergas have quite a bit of information on it, so they must be ahead of the pack on this stuff, I notice the intergas shop has a ultra fast recovery HWC -is that an upgrade you would recommend for a priority hot water system?

 

[muggles]

The IG Shop cylinder is excellent and definitely worth going for if you want DHWP

 

[MNW67]

its surprising how little information there is out there

I have found that as well. My experience is that many local installers are still in the dark about it. Finding someone to answer the question who has used that exact boiler might be difficult. I know you had the original article on PDHW. Did you read parts 2 & 3.

https://heatingacademynorthampton.co.uk/category/pdhw/

Vokera make good value system boilers. I believe @vulcancontinental knows lots about how to set them up to do priority hot water.

Alpha have info in their installation manual about how to do it.

Some of the big brands don't seem to make it very obvious.

Here's a video of it being done on an Ideal Vogue which explains the principle very well:

 

[Deleted member 267285]

I have found that as well. My experience is that many local installers are still in the dark about it. Finding someone to answer the question who has used that exact boiler might be difficult. I know you had the original article on PDHW. Did you read parts 2 & 3.

https://heatingacademynorthampton.co.uk/category/pdhw/

Vokera make good value system boilers. I believe @vulcancontinental knows lots about how to set them up to do priority hot water.

Alpha have info in their installation manual about how to do it.

Some of the big brands don't seem to make it very obvious.

Here's a video of it being done on an Ideal Vogue which explains the principle very well:

Yep, @vulcancontinental works for Vokera and @Sim777 did that video. I’m in the dark about it, as who I work for mainly install combi’s, which are pdhw anyway.

 

[vulcancontinental]

We don't sell the PDHW boiler in the UK so use a Vokera system boiler with EPH controls on OT and that's the way to do it.

 

[Notch7]

I have found that as well. My experience is that many local installers are still in the dark about it. Finding someone to answer the question who has used that exact boiler might be difficult. I know you had the original article on PDHW. Did you read parts 2 & 3.

https://heatingacademynorthampton.co.uk/category/pdhw/

Vokera make good value system boilers. I believe @vulcancontinental knows lots about how to set them up to do priority hot water.

Alpha have info in their installation manual about how to do it.

Some of the big brands don't seem to make it very obvious.

Here's a video of it being done on an Ideal Vogue which explains the principle very well:

Thanks, yes I've watched that video + read the other parts of PDHW blog.

I've seen a heating engineer post on another forum where he says he has fitted quite a few Baxi boilers with EPH controls set up for hot water priority....so I'm going to see if my heating engineer will do that system.

Apparently Baxi open therm doesn't work with some O/T controllers because it needs an ID as part of the signal.

I hear that the new Baxi system 2 boilers (introduced last July) have an updated PCB that is open therm certified....but what that means is unclear.

The new baxi system 2 also has dynamic range which links flow temperature to return temperature.

There is little information publicly available so it's hard to get a handle on PDHW.

 

[ianmcd]

However, the boiler now fires up periodically (roughly every hour or so) and heats the domestic hot water to 60c (even though it's set to 50c on the Nest and on the dial on front of the boiler). This didn't happen with the on/off thermostat. I thought it might be the Bacteria Prevention feature on the Nest,

Baxi 228 is a combi boiler, the nest E can not control anything to do with the HW temp it is simply a room thermostat and only controls the CH